This proposal is based on the idea that understanding the mode of interaction of photoreceptors and pigment epithelium will contribute to elucidation of those factors resulting in hereditary retinal disease and/or retinal detachment, major themes of eye research today. The idea is based on accumulated knowledge of the variety of ways that photoreceptors interact with pigment epithelium. Of particular interest are the developmental interrelationship relating to outer segment differentiation and turnover. This proposal approaches the problem by attempting to carefully characterize the membrane systems at the photoreceptor-pigment epithelium interface, the site at which interaction is lkely to occur. One aspect of the proposal is to characterize the surfaces of mature and developing cells of the photoreceptor-pigment epithelium complex with regard the saccharide composition using ultrastructural localization techniques for lectin binding. It is proposal that this analysis be carried out by relating surface characteristics to the nature of the interphotoreceptor matrix and to membrane architecture as revealed with freeze fracture techniques. The proposal also considers the mechanism of outer segment membrane assembly by developing pulse chase protocols for lectin binding studies which may localize sites of plasma membrane expansion. Another approach in this proposal is to analyze those factors maintaining normal photoreceptor-pigment epithelial adhesivity. This part of the proposal is based on an apparent light evoked increase in adhesivity and a model system for measurement of relative adhesivity in the complex. Finally, it is proposed to apply basic information gained regarding the interface to animal models of hereditary retinal disease.